I've used it before on antennas, but none of them stay in the air long enough to see how long it'll last.
Last edited:
-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
Homebrew Merlin Experiment
- Thread starter HomerBB
- Start date
Yep Booty, I was curious about the Merlin dimensions too.
Homer, did you ever get a chance to measure the coil for your 5/8 wave yet? If I could get the coil to work on my model, then I'd like to see if it made a difference to the results.
I don't think adding the coil will make a big difference in the gain/angle unless it adds a bunch of horizontal RF to the pattern...like my I-10K model does.
Homer, did you ever get a chance to measure the coil for your 5/8 wave yet? If I could get the coil to work on my model, then I'd like to see if it made a difference to the results.
I don't think adding the coil will make a big difference in the gain/angle unless it adds a bunch of horizontal RF to the pattern...like my I-10K model does.
@ Doc - It is a solid aluminum plate chromed on one side. I picked it up at a salvage store couple months ago for $9.
@ Marconi - I have measured the coil. It is 3-3/8" diameter x 5" tall. It isn't square, but I think it is close enough.
@ Marconi - I have measured the coil. It is 3-3/8" diameter x 5" tall. It isn't square, but I think it is close enough.
GP radials are installed. No more time today to do anymore. SWR is low on the band, but I want to try to fine tune it a little more.
Last edited:
Homer is the 5" coil height from the connections between the GP and the radiator, or is it the distance between the coils as noted in the attached image?
What is the wire diameter approximate?
Do you recall the overall length approximate and the spacing?
What is the tap wire length and diameter approximate?
View attachment Homer's .625 coil.pdf
from top of wraps (coils) to the bottom of the same is 5". There are 9 wraps.
1/4" copper tubing
8" from vertical connection to the GP connection. the spacing is approx 1/4" between the wraps. i tried to make them the same as the tubing.
the tap wire is #10 stranded and 8" long (approx 1/8" diameter)
Last edited:
I have had a second Merlin owner offer to fix me up with some exact measurements. I'm looking forward to that from either or both.
So far, things as they are, I have seen the conditions hand the performance edge by very small differences to either antenna.
I will say that over the past few days the Merlin has begun to show a trend of performance advantage reflecting its design intent. Until I double check my dimensions against the originals I anticipate coming to me soon (fingers crossed) I will not give a definitive statement to that point. On the other hand, if asked what I think at this point in the situation where someone was considering buying a full length 5/8 GP or a Merlin to run in a height restricted area, I would advise they consider an antenna such as this Merlin - Top One, Astroplane - that is designed to provide more consistent performance under the conditions.
Why I am leaning this way at the moment is:
Although there are no, again I repeat, zero S-units (bars) of difference on my meter except for when I reported earlier in the above thread for the 5/8 GP, the Merlin does report to my ears a detectable audio increase most often and most consistently. Regardless of the debate that will potentially ensue regarding how the human ear can not detect audio gains except with a given amount of measurable db increase, I will not rescind the statement. I, Homer, clearly can detect the difference. Some (or all) of this may be due to the fact that the noise floor is clearly lower for the Merlin with its feedpoint at 36' as opposed to the 5/8 GP fed at 19.5' with tip heights the same.
In as close as 10 - 15 miles the performance of either seems similar, but whichever has a quieter noise floor at the moment (usually the Merlin) becomes the antenna of choice. When I work local stations, mobile or base, beyond that distance out to 30 miles (I have not heard any farther out when I was in the shack) the Merlin has been better over 90% of the time.
Am I ready for a conclusion? As I said, not yet. I will be out of town over the next 5 days and will be unable to report on anything, nor make changes until afterwards, so the tweaks and tunes I will be making to both antennas will have to wait until after. It will only be then that I will say how I finally believe this washes out for the Same Tip Height Test (STHT).
I will likely be adding a twist to the .625 antenna before I am done. Claims to the effect that the I10k was bested by the Merlin has me considering adding a Top Hat of the dimensions that the I10k uses and run a test between the .625/.64 vertical configuration where both of the antennas potentially use the capacitance hat technology to adjust toward optimum current maximum on the vertical radiator.
So far, things as they are, I have seen the conditions hand the performance edge by very small differences to either antenna.
I will say that over the past few days the Merlin has begun to show a trend of performance advantage reflecting its design intent. Until I double check my dimensions against the originals I anticipate coming to me soon (fingers crossed) I will not give a definitive statement to that point. On the other hand, if asked what I think at this point in the situation where someone was considering buying a full length 5/8 GP or a Merlin to run in a height restricted area, I would advise they consider an antenna such as this Merlin - Top One, Astroplane - that is designed to provide more consistent performance under the conditions.
Why I am leaning this way at the moment is:
Although there are no, again I repeat, zero S-units (bars) of difference on my meter except for when I reported earlier in the above thread for the 5/8 GP, the Merlin does report to my ears a detectable audio increase most often and most consistently. Regardless of the debate that will potentially ensue regarding how the human ear can not detect audio gains except with a given amount of measurable db increase, I will not rescind the statement. I, Homer, clearly can detect the difference. Some (or all) of this may be due to the fact that the noise floor is clearly lower for the Merlin with its feedpoint at 36' as opposed to the 5/8 GP fed at 19.5' with tip heights the same.
In as close as 10 - 15 miles the performance of either seems similar, but whichever has a quieter noise floor at the moment (usually the Merlin) becomes the antenna of choice. When I work local stations, mobile or base, beyond that distance out to 30 miles (I have not heard any farther out when I was in the shack) the Merlin has been better over 90% of the time.
Am I ready for a conclusion? As I said, not yet. I will be out of town over the next 5 days and will be unable to report on anything, nor make changes until afterwards, so the tweaks and tunes I will be making to both antennas will have to wait until after. It will only be then that I will say how I finally believe this washes out for the Same Tip Height Test (STHT).
I will likely be adding a twist to the .625 antenna before I am done. Claims to the effect that the I10k was bested by the Merlin has me considering adding a Top Hat of the dimensions that the I10k uses and run a test between the .625/.64 vertical configuration where both of the antennas potentially use the capacitance hat technology to adjust toward optimum current maximum on the vertical radiator.
Last edited:
cool homer we will be waiting for ya. just wanted to say many thanks your testing
and building antennas and your conclusions have been most helpful. 1 more test
id like to see is your merlin vs astroplane same tip heights.my guess is they be
the same but ya never know
and building antennas and your conclusions have been most helpful. 1 more test
id like to see is your merlin vs astroplane same tip heights.my guess is they be
the same but ya never know
Others want to see this, too.
When I get another Astroplane built I just may have to give it a go.
Information is beginning to emerge from several sources to assist with the project, some of which others who'd like to give it a try will find useful:
I am still looking forward to a measurement of the distance between the center of the mast and the radials at a distance down from the hub. I will check mine again and determine whether they are at exactly 45° degrees angle until more detailed info arrives. I think they will be tighter than that by looking at the pictures - closer to 25° -30°.
And last, but not least, there is the wife ingredient that keeps us from having all the radio time we'd like to have . . .
*added for clarity
Turbo said:
I am good here except I will have to remove 1/2 turn of the coil.coolbreeze said:
Turbo said:
The length of the Cap Hat radials is the same from both of these sources, but there is a bit here that seems to indicate two different iterations of the Merlin. From other discussions/sources I am seeing a separation between the Hat and the Coil of only 1"coolbreeze said:
Turbo said:
I am good here, too. We know that tuning is apt to show small increments of differences in adjustment lengths from place-to-place.coolbreeze said:
Turbo said:
My radials are two piece units and are 4 instead of three, If anything, the 4 should be better, but certainly not a disadvantage to the antenna's performance.coolbreeze said:
Turbo said:
I am still looking forward to a measurement of the distance between the center of the mast and the radials at a distance down from the hub. I will check mine again and determine whether they are at exactly 45° degrees angle until more detailed info arrives. I think they will be tighter than that by looking at the pictures - closer to 25° -30°.
And last, but not least, there is the wife ingredient that keeps us from having all the radio time we'd like to have . . .
*added for clarity
sorry 4 the delay homer been busy with holidays and new year. seems this thread
died off . glad ya got more info on the orignal merlin. did ya have to change anything
on yours?any final comments on these tests
died off . glad ya got more info on the orignal merlin. did ya have to change anything
on yours?any final comments on these tests